Plants are a promising system for synthesis of foreign proteins due to their potential for low-cost high-volume production, ability to perform post-translational modifications, and lack of possible pathogen contamination. Many plant systems ranging from dicot model species such as tobacco and Arabidopsis to monocots including rice and maize have been used to express genes for disease resistance, enhanced nutrient quality, and production of pharmaceuticals and industrially valuable proteins (reviewed in Streatfield, 2007, Khan, 2010, Khan, in press). There has been a continued effort to increase and tightly regulate expression of proteins and products in plants.